WASHINGTON, United States (AFP) — US President Donald Trump's administration has refunded about $100 billion in tariffs since the Supreme Court struck down a wave of his duties this year, court filings show.

The figure, reported in documents Tuesday, constitutes about 60 percent of some $166 billion the Trump administration collected after invoking the International Emergency Economic Powers Act to impose duties.

The refunds went to importers that had paid the duties.

Trump used the act to impose sweeping tariffs on trading partners since returning to the White House last year, but the high court ruled in February this year that he had exceeded his authority in doing so.

This dealt a sharp blow to the president's ability to deploy tariffs at will, as he sought to use them as a tool for leverage against US allies and competitors alike.

The president's sector-specific tariffs, which rely on different justifications, remain intact.

In the court filing on Tuesday, a US Customs and Border Protection official said that as of 31 July, "approximately $128.68 billion in both potential and certified refunds" had been accepted for processing.

Of that total amount, refunds of around $100 billion had been completed and sent to the Treasury Department for disbursement, the official added.

Since the Supreme Court's ruling in February, Trump has turned to new means to reimpose tariffs on dozens of partners, sparking further court challenges.